Gene-Editing Milestone: Baby Receives First-Ever Personalized DNA Repair Treatment.

In a historic leap for personalized medicine, a baby boy named Kyle “KJ” Muldoon Jr. has become the first person to receive a gene-editing therapy designed specifically for him. Developed and deployed in under seven months, the custom-made drug aimed to correct a single-letter genetic mutation responsible for a rare and life-threatening metabolic disorder.

The innovative treatment was created using a refined form of CRISPR known as base editing, which enables scientists to swap a single DNA letter at a precise location. Unlike earlier gene-editing tools that typically deleted or disabled faulty genes, base editing allows for precise corrections—restoring gene function rather than removing it.

KJ’s condition was caused by a mutation in the CPS1 gene, preventing his body from producing a vital enzyme and causing dangerous ammonia buildup. Diagnosed shortly after birth in August, KJ’s symptoms were severe, and without intervention, the disorder is usually fatal unless treated with a liver transplant.

After identifying the specific genetic error through sequencing, researchers from the University of Pennsylvania, led by gene-editing expert Dr. Kiran Musunuru, proposed a radical solution: crafting a one-time drug to rewrite the mutation in KJ’s liver cells. With approval from the U.S. Food and Drug Administration, the team moved swiftly, testing the treatment in animals before administering it to the infant in escalating doses.

“This is the future of medicine,” said Dr. Musunuru. “One day, no child will have to die prematurely because of a single-letter mistake in their genes.”

The project, involving over 45 scientists, physicians, and biotech collaborators—many working pro bono—highlights both the potential and the challenge of individualized gene therapies. While the science has reached a point where such bespoke treatments are possible, the economics remain daunting. Because these conditions are so rare, companies find little financial incentive to develop therapies that may only help one patient.

“This particular drug will probably never be used again,” noted Dr. Rebecca Ahrens-Nicklas, a physician at the Children’s Hospital of Philadelphia who led the clinical effort. Nonetheless, she emphasized the collaborative nature of the achievement and its potential to reshape future treatment strategies.

Although a definitive assessment of the therapy’s success is pending—since a liver biopsy would be required to confirm gene correction—doctors are optimistic. KJ has received three escalating doses without complications and is showing encouraging signs of progress.

“He’s growing and thriving,” said Ahrens-Nicklas. “That tells us the editing may be at least partially effective. But it’s early days, and we need to monitor him closely to fully understand the long-term effects.”

This milestone also underscores a growing dilemma in modern gene therapy: the gap between technological capability and accessibility. While CRISPR-based tools are evolving rapidly, most current clinical trials focus on relatively common genetic conditions like sickle cell disease. The ultra-rare disorders, such as KJ’s, often fall through the cracks due to high development costs and lack of a viable commercial model.

Dr. Musunuru acknowledged the scalability issue, noting that his team and others are beginning to work on streamlining the development pipeline to make custom treatments faster and more affordable. He envisions a future in which genetic diagnoses at birth could be quickly followed by personalized therapies—initially for liver-based diseases, but potentially expanding to neurological and muscular conditions as delivery technologies improve.

KJ’s story is a powerful testament to what is possible when science, urgency, and collaboration converge. While his treatment may remain a one-time solution, it has opened the door to a new era of precision medicine—where even the rarest conditions may one day be curable at the genetic level.

Source:https://www.technologyreview.com/2025/05/15/1116524/this-baby-boy-was-treated-with-the-first-personalized-gene-editing-drug/

This is non-financial/medical advice and made using AI so could be wrong.